The Second Round Table Conference, 7 September 1931, with Zafarullah Khan seated to the rear of the table (closest to the camera)

Muhammad Zafarullah Khan was elected a member of the Punjab Legislative Council in 1926 and presided at the Delhi meeting of the All-India Muslim League in 1931, where he advocated the cause of the Indian Muslims through his presidential address. He participated at the Round Table Conferences held from 1930 to 1932 and became the Minister of Railways in May 1935. In 1939, he represented India at the League of Nations. He was appointed the Agent General of India in China in 1942 and represented India as the Indian Government's nominee at the Commonwealth Relations Conference in 1945, where he spoke on India's cause for freedom.

Lord Linlithgow, however, had not a complete grasp of contents in the analytic note prepared by Sir Zafarullah khan at the time it was sent to Secretary of India.[14] A copy of this note was sent to Jinnah. Sir Zafarullah khan's proposal of a two-state solution for Indian Federation was adopted by the Muslim League with a view to give it full publicity in the forthcoming session at Lahore 22–24 March.

In September 1941, Zafarullah Khan was appointed a Judge of the Federal Court of India, a position he held until June 1947. At the request of Muhammad Ali Jinnah, he represented the Muslim League in July 1947 before the Radcliffe Boundary Commission and presented the case of the Muslims in a highly commendable manner. Zafarullah Khan advised the Nawab of Junagadh that if he decided to join his state with Pakistan, it would be both moral and legal. The Nawab then proceeded to announce his decision.[15]

As Foreign Minister, he represented Pakistan at the Manila Treaty Conference in September 1954. Support for the Manila Pact in Pakistan was divided, with West Pakistan dominated army and a handful of leaders in favour of this, while most elected members of the Constituent Assembly from West Pakistan and all of the Assembly members from East Pakistan opposed it. Zafarullah signed the Manila Pact, committing Pakistan's accession to the Southeast Asia Treaty Organization (SEATO).

Zafarullah Khan in Japan, along with Japanese converts to the Ahmadiyya movement.

As an Ahmadi, Zafarullah Khan held the office of Ameer (president) of the Lahore, Pakistan chapter of the Community from 1919 to 1935.[2] He served as Secretary to Khalifatul Masih II, the second successor of Mirza Ghulam Ahmad, at the Majlis-e-Shura (Consultative Council) for the first time in 1924, and continued to do so for 17 more sessions. In addition, he was a member of the delegation which represented the Ahmadiyya Community at the All Parties Conference held in 1924. In 1927, he acted successfully as representative counsel for the Muslims of the Punjab in the contempt of court case against the Muslim Outlook.[2]

As Pakistan's first Foreign Minister, Zafarullah Khan addressed the Constituent Assembly of Pakistan in the days leading up to the passing of the Objectives Resolution. The Objectives Resolution, which combined features of both Western and Islamic democracy, is one of the most important documents in the constitutional history of Pakistan. It was designed to provide equal rights for all citizens of Pakistan, regardless of their race, religion or background. Zafarullah Khan was quoted as saying:

It is a matter of great sorrow that, mainly through mistaken notions of zeal, the Muslims have during the period of decline earned for themselves an unenviable reputation for intolerance. But that is not the fault of Islam. Islam has from the beginning proclaimed and inculcated the widest tolerance. For instance, so far as freedom of conscience is concerned the Quran says "There shall be no compulsion" of faith...[17]

In March 1958, Zafarullah Khan performed Umrah and, at the same time, visited the shrine of Muhammad in Medina, Saudi Arabia. During his visit, he met with the King of Saudi Arabia Ibn Saud of Saudi Arabia, and stayed at the Royal Palace as a personal guest of the king. In 1967, he returned to Saudi Arabia to perform Hajj, a religious duty that must be carried out at least once in a lifetime by every able-bodied Muslim who can afford to do so.

Khan's legacy has been hailed and his paramount role in the creation of Pakistan has been celebrated in the history of Pakistan. He is popularly known by his title Sir. Zafarullah Khan openly acknowledged that he belonged to the Ahmadiyya Community. He was selected by Muhammad Ali Jinnah as first Foreign Minister of Pakistan. He was one of the most influential, skilled, and passionate diplomats of his time.

He was indeed a champion of the Arab cause and his ceaseless efforts whether among the Muslim and non-aligned countries or at the International Court of Justice will remain forever a shining example of a great man truly dedicated to our faith and civilization.

In fact, it was not possible for any Arab, however capable and competent he may be, to serve the cause of Palestine in a manner in which this distinguished and great man dedicated himself. What was the result of the debate in the United Nations is another matter. But, it must be acknowledged that Mohammad Zafrulla Khan occupies a pre-eminent position in defending the Palestinians in this dispute. We expect from all Arabs and followers of Islam that they will never forget this great Muslim fighter. After Palestine, the services of this man for the independence of Libya also deserves admiration. In the United Nations, his struggle for the rights of Arabs formed the basis of firm and lasting friendship between us.